A large amount of so called information is in people's minds and memory's, we know how good that is! Depending on what's being talked about, we remember how cold it was, or how hot, wet, dry, etc. And there has never been a winter, summer, spring, fall, better or worse then that one!
Yes, I do know about ice cores being taken and studied, temputures recorded and studied, winds, rainfall, and on and on. In general, our record keeping does not go back very far, and anything that does, is in many cases thrown out with the wash water. A statement would be " that can't be right"! What the!?.
Am I a nay sayer, no not in anyway. It is just very hard to find the grain in the straw.
A story, which is in some history books, the Vikings were running around some time ago, around about 1200+/-. Got to Iceland, decided, pretty nice here, started farming, growing crops, raising animals, some settlements. Anyhuw, about 1430+/-, it started getting colder, couldn't grow crops and so on, most of them pulled out and went back to the Scandinavian country's.
In hand with that, it seems there was not a winter festival? on the Thames river in England before 1430+/-. No ice, not thick enough?? It seems that when it did happen, it lasted many 100's of years.
There was also a period of time around there that barely any crops grew, 3-5 +/- years, at least in Europe. Was recorded as, very wet, cloudy, lack of sun, cold, the Great Famine. The Black plague and the Dark ages had a go around then too. Something's maybe human caused, some not.
As to our present day record keeping, be careful where that info comes from, and HOW it is recorded. Sometimes its an average and peaks, high and low are laying with the wash water, as that can't be right, gauges were not working right, they can't see past their nose etc.
Is the world or some, all of it warming up, I do think so. It appears, once again, there maybe a "Northern Passage". Are the summers hotter, or are the hot times lasting longer with less rain. A cycle?
Perhaps, 7 billion plus people, with a body temputure of 98.5+/- are slowly warming things up. Seems most want a hot meal once a day too, and a warm place to sleep or a cool place to get out of the heat, some of which uses energy forms to make.
And things change, some slow, some fast.
I am not sure long the planet is now "thought" to have been, there have been changes!!
What do I know, not very dam much in the big show.